US President Donald Trump never liked the 2015 Joint Comprehensive Plan of Action (JCPOA) nuclear deal signed between Iran and key global powers, under which the Iranians agreed to temporary restrictions and close monitoring of their nuclear programme, in return for the lifting of most international sanctions.
And if current indications from Washington prove correct, Mr Trump will strike this week at the very foundations of the JCPOA by refusing to certify that Iran remains in compliance with it, notwithstanding the fact that the International Atomic Energy Agency confirmed on eight consecutive occasions that Iran respected its nuclear obligations.
The process of certification by the White House is a purely American one, mandated by the US Congress rather than required by the JCPOA text. So, Mr Trump's potential decertification would not necessarily mean Iran has failed to comply with the deal, and does not even mean the US itself will immediately abandon the deal. Nor is it evident that the US Congress will seize this chance to reimpose sanctions on Iran. The Republicans hold a narrow 52-48 majority in the Senate, not enough to overcome likely filibustering from the Democrats.
Still, Mr Trump's move will create a deep rift between the US and its key European allies - Britain, France and Germany - who accept that while the JCPOA is not perfect, it remains the only peaceful hope of restraining Iran's nuclear ambitions.
Mr Trump's actions will also alienate Russia and China, the deal's other signatories. And the idea that the US can play fast and loose with the interpretation of global nuclear treaties is a poor example to North Korea, where governments are trying to promote a similar negotiated arrangement.
The real danger is that Mr Trump's actions will unleash a downward spiral of confrontations between Iran and the US that will plunge the entire Middle East into further turmoil.